Abstract:

AIM: To examine false-positive HIV DNA polymerase chain reaction
(PCR) test results in children, and the potential implications for the
paediatric HIV epidemic in sub-Saharan Africa.
METHODS: A review was done of records over a 6-year period
of children less than 18 months old at an HIV treatment site in
South Africa, to evaluate those with an initial ‘false’-positive HIV
DNA PCR result, but later proven to be HIV-uninfected with HIV
DNA PCR and/or quantitative HIV RNA PCR tests. We calculated
the influence of changing HIV transmission rates on predictive
values (PV) of HIV DNA PCR tests in a hypothetical population
of all HIV-exposed infants over a 1-year period. (Positive PV:
proportion of individuals with a positive test with disease; negative
PV: proportion of individuals with negative test and no disease).
ReSULTS: Of 718 children, 40 with an initial positive HIV DNA
PCR test were subsequently proven to be HIV-uninfected, resulting
in a positive PV of 94.4%. Most (75%) uninfected children
had PMTCT interventions and were asymptomatic or mildly
symptomatic (77.5%). Calculations using a test specificity of 99.4%,
as reported previously, show a decrease in positive PV using a
single-test strategy from 98.6% at 30% HIV transmission rate, to
94.8% at 10% transmission, to 62.5% at 1% transmission. Reduction
in test specificity further decreases positive PV at low transmission
rates.
CONCLUSION: Decreasing mother-to-child HIV transmission rates
reduce the positive predictive value of a single HIV DNA PCR test
result, necessitating adaptations to diagnostic algorithms to avoid
misdiagnosis and inappropriate treatment, especially with early
initiation of antiretroviral therapy in asymptomatic infants.